Prevention of thermal aggregation of an allosteric protein by small molecules: some mechanistic insights

Detailed knowledge of conformation and dynamics of native, intermediate and unfolded states of a protein is essential in searching for effective small molecules to prevent its aggregation. In a recent study we have demonstrated how allosteric effectors may influence protein-protein interactions at high temperatures using glutamate dehydrogenase (GDH) as a model allosteric protein. In the present study, thermal aggregation of this well-characterized enzyme was investigated in the presence of a number of amino acids (including Gly, Glu, Trp, Pro, Lys, Arg), polyamines (putrescine and spermidine) and chaperone-like molecules (cyclodextrins and caseins) as non-specific effectors. It was shown that some amino acids and polyamines may suppress aggregation via interaction with native species and may preserve the activity of the enzyme while cyclodextrins and caseins may exert their anti-aggregation potential via binding to aggregation-prone intermediates, without having any capacity to protect its native structure from unfolding. Observations describing the similarities and differences between the specific ligands and non-specific small molecules related to their interaction with native and aggregation-prone states of GDH are presented and discussed. It is argued that the type of studies described in the present communication is useful for the development of effective strategies for prevention of aggregation by small molecules.